1. Field of the Invention
The invention relates to a tamper-evident closure for a syringe having a plastic connection end with a Luer connection and a cap and a frangible web formed as a single injection molded part, wherein the cap is fitted to the Luer connection.
2. Description of the Related Art
With syringes, in particular prefilled syringes, one provides a tamper-evident closure which ensures the integrity for the user, i.e. the integrity of the closure and thus of the medium filled into the syringe. Such tamper-evident closures are counted as belong to the state of the art and are known for example from U.S. Pat. No. 5,135,496. This document discloses a glass cylinder on whose end there is attached a component consisting of plastic which comprises a Luer connection onto which later the cannula is placed in a manner known per se, or via which the syringe is connected in another manner. This Luer connection is sealingly closed with a plug which completely encompasses the free end on the inside and well as on the outside. This plug is held by a plastic cap which is connected via a frangible web to a ring as a fixation component. This ring comprises a projection which engages into a corresponding recess at the connection-side end of the syringe and firmly holds this here. With this, the cap, the frangible web and the ring are typically formed as one piece as an injection molded part and are pushed over the connection-side end of the syringe until the projection locks on the ring at the connection-side end.
The problem with such tamper-evident closures which are pushed onto the connection-side end of the syringe in a locking manner is that the manufacturing tolerances are relatively tight in order to ensure that on removal of the cap it is indeed the frangible web that breaks and not the connection between the fixation ring and the connection-side end of the syringe. Then specifically the closure may be placed on again without further ado without the integrity and thus the sterility of the product being guaranteed. There further exists the danger that the frangible web breaks by way of buckling or overstretching already when being placed on. Moreover the frangible web is often designed so solid that a removal of the cap by exerting tension forces alone is not sufficient, and that rather the cap is additionally rotated with respect to the fixation ring by way of hand force. However both hands are then required, one for gripping the fixation ring and the other for gripping the cap. Disregarding the fact that this is awkward, with the medical syringes being discussed here there particularly exists the danger that germs may get into this region by way of this. A thinner dimensioning of the frangible web is often not at all possible or only very difficult to realize with regard to tooling technology since specifically the fixation ring during the injection molding procedure as a rule must be filled with plastic via the frangible web, so that for this reason alone a certain minimum cross section needs to be present in order to ensure a complete filling of the fixation ring during the injection molding procedure.